text: /*
   * Copyright (C) 2008 Apple Inc. All Rights Reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  /**
   * @implements {Common.EventTarget}
   * @unrestricted
   */
  Common.Object = class {
    /**
     * @override
     * @param {string|symbol} eventType
     * @param {function(!Common.Event)} listener
     * @param {!Object=} thisObject
     * @return {!Common.EventTarget.EventDescriptor}
     */
    addEventListener(eventType, listener, thisObject) {
      if (!listener)
        console.assert(false);
  
      if (!this._listeners)
        this._listeners = new Map();
      if (!this._listeners.has(eventType))
        this._listeners.set(eventType, []);
      this._listeners.get(eventType).push({thisObject: thisObject, listener: listener});
      return new Common.EventTarget.EventDescriptor(this, eventType, thisObject, listener);
    }
  
    /**
     * @override
     * @param {string|symbol} eventType
     * @param {function(!Common.Event)} listener
     * @param {!Object=} thisObject
     */
    removeEventListener(eventType, listener, thisObject) {
      console.assert(listener);
  
      if (!this._listeners || !this._listeners.has(eventType))
        return;
      var listeners = this._listeners.get(eventType);
      for (var i = 0; i < listeners.length; ++i) {
        if (listeners[i].listener === listener && listeners[i].thisObject === thisObject)
          listeners.splice(i--, 1);
      }
  
      if (!listeners.length)
        this._listeners.delete(eventType);
    }
  
    /**
     * @override
     */
    removeAllListeners() {
      delete this._listeners;
    }
  
    /**
     * @override
     * @param {string|symbol} eventType
     * @return {boolean}
     */
    hasEventListeners(eventType) {
      return this._listeners && this._listeners.has(eventType);
    }
  
    /**
     * @override
     * @param {string|symbol} eventType
     * @param {*=} eventData
     * @return {boolean}
     */
    dispatchEventToListeners(eventType, eventData) {
      if (!this._listeners || !this._listeners.has(eventType))
        return false;
  
      var event = new Common.Event(this, eventType, eventData);
      var listeners = this._listeners.get(eventType).slice(0);
      for (var i = 0; i < listeners.length; ++i) {
        listeners[i].listener.call(listeners[i].thisObject, event);
        if (event._stoppedPropagation)
          break;
      }
  
      return event.defaultPrevented;
    }
  };
  
  /**
   * @unrestricted
   */
  Common.Event = class {
    /**
     * @param {!Common.EventTarget} target
     * @param {string|symbol} type
     * @param {*=} data
     */
    constructor(target, type, data) {
      this.target = target;
      this.type = type;
      this.data = data;
      this.defaultPrevented = false;
      this._stoppedPropagation = false;
    }
  
    stopPropagation() {
      this._stoppedPropagation = true;
    }
  
    preventDefault() {
      this.defaultPrevented = true;
    }
  
    /**
     * @param {boolean=} preventDefault
     */
    consume(preventDefault) {
      this.stopPropagation();
      if (preventDefault)
        this.preventDefault();
    }
  };
  
  /**
   * @interface
   */
  Common.EventTarget = function() {};
  
  /**
   * @param {!Array<!Common.EventTarget.EventDescriptor>} eventList
   */
  Common.EventTarget.removeEventListeners = function(eventList) {
    for (var i = 0; i < eventList.length; ++i) {
      var eventInfo = eventList[i];
      eventInfo.eventTarget.removeEventListener(eventInfo.eventType, eventInfo.method, eventInfo.receiver);
    }
    // Do not hold references on unused event descriptors.
    eventList.splice(0, eventList.length);
  };
  
  Common.EventTarget.prototype = {
    /**
     * @param {string|symbol} eventType
     * @param {function(!Common.Event)} listener
     * @param {!Object=} thisObject
     * @return {!Common.EventTarget.EventDescriptor}
     */
    addEventListener: function(eventType, listener, thisObject) {},
  
    /**
     * @param {string|symbol} eventType
     * @param {function(!Common.Event)} listener
     * @param {!Object=} thisObject
     */
    removeEventListener: function(eventType, listener, thisObject) {},
  
    removeAllListeners: function() {},
  
    /**
     * @param {string|symbol} eventType
     * @return {boolean}
     */
    hasEventListeners: function(eventType) {},
  
    /**
     * @param {string|symbol} eventType
     * @param {*=} eventData
     * @return {boolean}
     */
    dispatchEventToListeners: function(eventType, eventData) {},
  };
  
  /**
   * @unrestricted
   */
  Common.EventTarget.EventDescriptor = class {
    /**
     * @param {!Common.EventTarget} eventTarget
     * @param {string|symbol} eventType
     * @param {(!Object|undefined)} receiver
     * @param {function(?):?} method
     */
    constructor(eventTarget, eventType, receiver, method) {
      this.eventTarget = eventTarget;
      this.eventType = eventType;
      this.receiver = receiver;
      this.method = method;
    }
  };
  